In the related art, in a sensor chip including a pixel array which converts incident light to electrical signals, a so-called bare chip mounting structure in which a chip is mounted directly on a glass substrate is known. In the bare chip mounting structure, the electrical signals output from the sensor chip are output outside the glass substrate through wiring patterns provided on the glass substrate (for example, see Patent Documents 1 and 2).
In recent years, in a large sensor chip which is used in a so-called digital single lens reflex camera, there is demand for a higher-speed operation, and an A/D converter is provided for each column of the pixel array on the same chip to perform signal processing in parallel, thereby suppressing the processing speed of the A/D converter to be comparatively lower and thus achieving low power consumption. However, in order to achieve higher-speed processing, since a sensor unit which has a large dynamic range with low noise and a high power supply voltage and a digital circuit in which a fine transistor is provided to perform an ultra high-speed operation with a lower power supply voltage are constituted by a single chip, a manufacturing process becomes complicated, and yield is degraded. During a high-speed operation, heat generation of the chip, especially, heat generation of the A/D converter, may increase, thereby causing degradation in image quality or the like in the pixel array due to a rise in temperature.
For this reason, in order to block heat transfer from the A/D converter to the pixel array, a so-called multi-chip mounting structure in which a signal processing unit including an A/D converter and a pixel array are constituted by individual chips and mounted on a single glass chip may be made.
In this case, a sensor chip is disposed substantially at the center of the substrate, and an FPC (flexible printed circuit board) or the like is connected to an external connection portion on one side of the glass substrate. The signal processing chip is disposed between the sensor chip and the external connection portion, and multiple signal lines from the signal processing chip are connected to the external connection portion. Power for driving the sensor chip to be supplied through the FPC, clock signals, and the like are directly supplied from the external connection portion to the sensor chip through pattern wiring on the glass substrate.